Figure 2.

Identification of key amino acids of AMY₃R ECL2 and ECL3 for peptide binding affinity (log K_i). (A) sCT; (B) hCT; (C) pCT; (D) rAmy; (E) hCGRP. Mutations that significantly decreased peptide affinity in radioligand competition assay are colored dark orange (≤10-fold effect) or red (>10-fold effect), with mutated amino acids without significant alteration to log K_i colored gray. Amino acid mutations where there was an insufficiently robust functional effect to quantify by radioligand competition binding are depicted in black. The receptor ECD is not shown for clarity, with the CTR TM bundle in blue ribbon and RAMP3 in green ribbon. Quantitative data are reported in Table 1.